Summary
BW Vulpeculae or BW Vul, is a variable star in the northern constellation of Vulpecula. It is near the lower limit of visibility to the naked eye with a typical apparent visual magnitude of 6.54.[3] Based on an annual parallax shift of 1.15 mas,[2] the distance to BW Vul is about 2,800 light years. It is moving closer to the Earth with a baseline heliocentric radial velocity of around −6 km/s.[8]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 54m 22.39491s[2] |
| Declination | +28° 31′ 19.1827″[2] |
| Apparent magnitude (V) | 6.54[3] (6.44 – 6.68)[4] |
| Characteristics | |
| Spectral type | B2 IIIv[5] |
| U−B color index | −0.147±0.011[6] |
| Variable type | β Cep[7] |
| Astrometry | |
| Radial velocity (Rv) | −6.1±3.0[8] km/s |
| Proper motion (μ) | RA: +0.437[2] mas/yr Dec.: −4.981[2] mas/yr |
| Parallax (π) | 1.1494 ± 0.0652 mas[2] |
| Distance | 2,800 ± 200 ly (870 ± 50 pc) |
| Absolute magnitude (MV) | −2.47[9] |
| Details | |
| Mass | 6.8±0.1[10] or 11−14[11] M☉ |
| Luminosity | 515.14[6] L☉ |
| Surface gravity (log g) | 3.71[12] cgs |
| Temperature | 23,014+919 −883[12] K |
| Metallicity [Fe/H] | 0.07±0.12[12] dex |
| Rotational velocity (v sin i) | 24±6[3] km/s |
| Age | 3.4±2.5[10] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a B-type giant star with a stellar classification of B2 IIIv,[5] where the 'v' suffix indicates variability in spectral features. Various authors have printed mass estimates ranging from 11 to 14 times the mass of the Sun,[11] although Tetzlaff et al. (2011) gives a mass of just 6.8 M☉.[10] It is about 3.4[10] million years old and is spinning with a projected rotational velocity of 24 km/s.[3] The star is typically radiating 515[6] times the Sun's luminosity from its photosphere at an effective temperature of 23,014 K.[12]
The variability of this star was announced in 1937, at the 58th Meeting of the American Astronomical Society by Canadian astronomer, Robert Methven Petrie.[14] It is a Beta Cephei variable that ranges between magnitudes 6.44 and 6.68 over a period of 4.8 hours.[4] For unknown reasons, the periodicity of the star has undergone sudden changes, followed by long periods of stability.[15] BW Vul is one of the most extreme β Cephei stars in terms of variability of light and radial velocity.[3][16] This is hypothesized as being due to the star's relatively high metallicity, meaning the abundance of elements other than hydrogen and helium.[11] A distinctive feature of its radial velocity cycle is a unique "standstill" feature, which is caused by a shockwave generated by infall of material from a previous cycle.[16]
References edit
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- ^ a b c d e Stankov, A.; et al. (September 2003). "Abundances and radial velocity analysis of BW Vulpeculae". Astronomy and Astrophysics. 408 (3): 1077–1086. Bibcode:2003A&A...408.1077S. doi:10.1051/0004-6361:20031005.
- ^ a b Otero, Sebastian Alberto (21 November 2011). "BW Vulpeculae". AAVSO Website. American Association of Variable Star Observers. Retrieved 2 August 2015.
- ^ a b Lynds, C. R. (September 1959). "The light-variability of early B giants". Astrophysical Journal. 130: 577. Bibcode:1959ApJ...130..577L. doi:10.1086/146747.
- ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Gontcharov, G. A. (November 2012). "Spatial distribution and kinematics of OB stars". Astronomy Letters. 38 (11): 694–706. arXiv:1606.09028. Bibcode:2012AstL...38..694G. doi:10.1134/S1063773712110035. S2CID 119108982.
- ^ a b c d Tetzlaff, N.; et al. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
- ^ a b c Fokin, A.; et al. (November 2004). "Hydrodynamic models for β Cephei variables. I. BW Vulpeculae revisited". Astronomy and Astrophysics. 426 (2): 687–693. Bibcode:2004A&A...426..687F. doi:10.1051/0004-6361:20040418.
- ^ a b c d Niemczura, E.; Daszyńska-Daszkiewicz, J. (April 2005). "Metallicities of the β Cephei stars from low-resolution ultraviolet spectra". Astronomy and Astrophysics. 433 (2): 659–669. arXiv:astro-ph/0410440. Bibcode:2005A&A...433..659N. doi:10.1051/0004-6361:20040396. S2CID 14295631.. Note: value taken from [m/H].
- ^ "BW Vul". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 7, 2018.
- ^ Petrie, R. M. (1939). "A new Beta Canis Majoris-type star". Publications of the American Astronomical Society. 9: 53. Bibcode:1939PAAS....9Q..53P.
- ^ Odell, A. P. (August 2012). "Period variation in BW Vulpeculae redux". Astronomy & Astrophysics. 544: 4. arXiv:1205.5996. Bibcode:2012A&A...544A..28O. doi:10.1051/0004-6361/201219418. S2CID 119279687. A28.
- ^ a b Smith, Myron A.; et al. (December 2005). "Far-Ultraviolet and Optical Observations of BW Vulpeculae". The Astrophysical Journal. 634 (2): 1300–1310. Bibcode:2005ApJ...634.1300S. doi:10.1086/497026.